Muffler



Mal'Ch 14, 1939- G. c. sTARKwEATHr-:R E-r Al. 2,150,811

MUFFLER Filed March ll0, 1937 3 Sheets-.Sheet Q Ibm, K\

March 14, 19392 (g.l Cl STARKWEATER ET AL 2,150,811

MUFFLER 19437 5 Sheets-sham 2 Filed March l0,

Q m, mw la um O um w m @hw M @H 0 0\O 0 O 0000 o 0000 @0000 nH Q@Swo0000 MMO www r@ wr Q@ m% 1Q MUFFLER Filed March 10, 1937 5 sheets-sheet3 G. C. STARKWEATHER ET ALy March 14, 1939.

5. y E Ma w d@ T E u WM n We@ Nu?, .l

Patented Mar. 14, 1939 PATENT JoFFlcla- 2.150,81; Homan.

een. c. stu-kmh, Kenmare, ma Lucien L. Haas, Builalo, N. Y., assignorsto Buil'alo Pressed Steel Company, Buil'alo, N. Y.

ppueauon Much 1|,

This invention' relates to improvements in muillers or silencers for usein silencing the noises of the exhaust of an internal combustion engine.

One of the objects of this invention is to provide an improved mulllerof the type in which the gases are caused by bailles or the like t0change their direction of ilow while passing through the muiller, with aresonator chamber. Another object of the invention is to provide amuilier of this type in which a chamber is provided into which surgesor` peaks of pressure waves may pass to provide a more uniform ilow ofgases through other parts of the mumer.

Another object of the invention is to provide a muiiier of this typewith a resonator chamber which acts upon the sound waves to reduce noiseby destructive interference.

Other objects of this invention will appear from the followingdescription and claims.

In the accompanying drawings:

Fig. 1 is a longitudinal central sectional view of a muilier embodyingthis invention.

FigsjZ and 3 are transverse sections thereof respectively on lines 2-2and 3 3, Fig. l.

Fig. 4 is a fragmentary longitudinal sectional elevation of one end of amuiller oi' slightly modied construction.

Fig. 5 is a longitudinal central sectional view of a muiler of modifiedconstruction.

Fig. 6 is a transverse sectional view thereof, on line 6 5, Fig. 5.

Fig. 7 is a, fragmentary longitudinal central sectional view of one endof the muiiler shown in Fig. 5, with a slight modication.

Fig. 8 is a longitudinal central sectional view of a muiiler of stillanother modified construction.

Figs. 9 and l0 are transverse sectional views respectively on lines 9 9and lil-l0, Fig. 8.

Fig. l1 is a fragmentary longitudinal central sectional view of aportion of the muilier'shown' in Fig. 8, with a slight modiilcation.

We have found that if a mumer of the type in which the gases in passingthrough the same are caused by bailles, shells or the like,'to changetheir direction of ow a number of times, is provided with a resonatorchamber, superior results can be obtained not only insofar as thesilencing of sound waves is concerned, but also in that the resistanceto the ilow of gases through the muliler will be reduced by the use ofsuch resonator chamber which acts as an equalizing chamber for thepressure impulses, so that the back pressure heretofore produced bymuillers of this type is reduced.

1932, Serial No. 130,158

We have illustrated by way of example several forms of mumers ofthistype embodying our invention and it will be understood that themuiilers shown are merely illustrative of our invention and that it isnot intended to limit this invention to the particular constructionsshown.

In Fig. 1, a muiller is shown having a suitable housing or enclosurewhich may, for example.

include an outer shell l5 and end heads IB and lo I'I. The head I8 isprovided with a tubular extension or duct I8 adapted to receive anexhaust pipe I9 and the other head I1 is provided with a similar duct ortubular portion 20 through which the gases are discharged i'rom themuiller and to which the usual tail pipe (not shown) may be secured. Themumer includes an inner shell or conduit 22 and a pair of intermediateshells 23 and 24, which are spaced from each other and from the conduit22 and outer shell II to form spaces or chambers 25, 28 and 21.

The conduit and shells may be supported within the muiller in anysuitable or desired manner. In the particular construction shown, astepped cone or supporting member is provided which has a substantiallycylindrical outer portion 30 adapted to it Within an annular cylindricalpart 3| of the inlet head lli. This cylindrical part 30 of the shellsupport also is arranged to telescope ywithin the adjacent end of theintermediate shell 23 to support the same. The shell support has anothercylindrical portion or shoulder 32 of smaller diameter which is adaptedto telescope within the adjacent end oi' the inner conduit 22. The shellsupport may, if desired, be provided with an additional cylindricalportion 33 of still smaller diameter which extends into the conduit -22and which may receive the inner end of the exhaust pipe i9 as shown inFig. 1. At the other end of the muiiler, the discharge head I1 is pro-40 vided with a cylindrical portion or shoulder 35 within which theshell 23 may nt. The other intermediate shell 24 of larger diameter maybe supported in the muiller in any suitable manner, for example, byproviding the opposite ends thereof with inwardly pressed projections orparts 31 which rest against and which may be welded to the intermediateshell 23 as indicated at 3l. Any other means for securing the shells incorrect relation to each other and to the muiller may, of course, beemployed in place of those shown, and the connecting or telescopingparts of shells, heads, bailles and shell supports may be weldedtogether or otherwise secured, or may be lett to slide relatively toeach other to compensate for expanison and contraction due to unequalheating of different parts oi' the muiher dur ing use. i

The other or rear end oi the conduit 22 may be supported in correctrelation to the inner lshell by means of a baille 40 having an outercylindrical portion 4| which may be welded or otherwise secured to theshell 22 and having a second cylindrical portion 42 of smaller diameterwhich may telescope into the other end of the conduit 22. This bauleincludes a transverse wall 43 which closes the rear end of the innerconduit 22.

The inner conduit is provided with a discharge opening; which may be inthe form ci a series oi-apertures 45 through which the gases may flowfrom the inner shell 22 into the chamber 25 between this conduit and theintermediate shell 23. The intermediate shell 23 is provided f l with anopening or apertures 48, preferably 1ocated at a distance from theapertures of the conduit 22, for example,near the inlet head IB of themulder, and the gases and sound waves may, consequently, be dischargedthrough these apertures from the chamber 25 into the chamber 28. Theintermediate shell 23 near the discharge end of the muiiier and beyondthe baille "42 is provided with a series oi apertures 41 through whichthe gases iiow from the chamber 26 into the chamber 48 formed at therear end o! the shell 2l between the baille 40 and the head I1. Theintermediate shell 24 is also provided with means for communicating withthe outer chamber 21 of the mumer and any suitable means for thispurpose may be employed, such for example as a series of apertures 49.

In the operation of the muiiler, the exhaust gases from the engine aredischarged through the exhaust pipe Il, into the inner conduit or shell22 inthe form of a series of pressure pulsations Vor waves, which areaccompanied with sound waves. The gases pass to near the end of theshell 22 and are then discharged through the apertm'es 45 into thechamber 25, from which they pass through the apertures 46 into thechamber 2l. During the crest or peak of a pressure wave, some of thegases pass into the chamber 26 through the apertures 4! into the outeror resonatorchamber. Aiterapressurepeakhaspassed out of the chamber 26,some of the accumulated Vgas in the resonator and equalizing chamber 21'is discharged back into the chamber 26. Sound wavesalso pass throughthese apertures 49 into the r and equalizlng chamber and then backthrough the same aperture into the chamber 2l, at which time they willbe out of phase with similar sound waves in the chamber 28. The gasesand any remaining or modified sound waves then continue to ow lengthwiseinto the charnber 2i through the apertures 41 in the chamber 4I fromwhich they are discharged from the mullet. Y

The resonator chamber 21 in addition to its silencing elect upon thesound waves, thus also serves a very useful purpose of equalizing theflow of gases so that when a surge of gas enters the chamber 2i,following the opening of an `exhaust valve, aportion of this gas willenter into the chamber 21 and will again be discharged into the chamber2C during the trough of the pressure wave or impulse. This results in asteady iiow o! 'gas through the passage or chamber 2l and through theapertures 41, chamber 48, and through the tail pipe. This steady flowresults in a material reduction in the resistance to the tlow, andconsequently, results in a reduction in the back pressure of the muiher,as well as producing a very excellent silencing of' the exhaust noises.

In- Flg. 4 is shown an end of a muffler similar to the one shown inFigs. l to 3 inclusive; except for the following changes: The mufflershown in Fig. 4 has a second intermediate shell 52 correspending to theshell 24 oi the muilier shown in Figs. 1 to 3. The ends of the shell 52are also provided with depressions or inwardly pressed portions 53corresponding to the parts 31 oi the shell 24, forming portions orchannels 54. 'Ihe muiiler shown in Fig 4 differs from that shown inFigs. 1 to 3 in that the end of the shell 52 is spaced from the head IB.so that the channels 54 are utilized to carry the gases and sound wavesfrom the chamber 55 formed between the two intermediate shells 23 and 52into the outer resonance chamber 5B formed between the outer shell l5and the intermediate shell 52. The channels 54` consequently, formbottle necks for the resonator chamber 5B, and the wave lengths to whichthe chambers respond can be varied by changing the cross section andlength oi the bottle necks. Inconnection with this construction, it isalso possible to divide the outer space between the shells 52 and i5into two resonator chambers 56 and 51 by means oi an annular transversebaille 58. 'I'his baille can, consequent ly, be moved lengthwise oi thespace between the shells |5'and 52 so that the chamber 56 may be tunedin accordance with the particular sound waves which it is desired tosilence by destructive interference. Obviously, if two resonatorchambers are desired', the opposite Vend of the intermediate shell 52may be similarly formed to communicate with the chamber 51. Theoperation of this muiiler is similar to that oi the muilier shown inFigs. 1 to 3.

The modified form of our invention shown in Figs. 5 and 6, includes anouter shell 60 which with the heads Si and 62 forms an enclosure orhousing for the muiiier. The heads shown are similar in construction tothose described in connection with the muiiiers shown in Figs. 1 to i,to form tubular extensions or ducts for connection with exhaust and tailpipes. 'I'he muiiler is also provided with a supporting member E3 in theform of a stepped cone to which an inner shell or conduit 64 is secured.In this construction, however, only one intermediate shell 65 isemployed which is suitably welded or otherwise secured to a cylindricalshoulder or part 6G of the inlet head El, and the supporting member 63has an outer cylindrical portion 61 welded or otherwise secured to theinner face of the intermediate shell 65. The other end of theintermediate shell may be telescopically arranged within a.substantially cylindrical shoulder B8 of the head 62 and welded thereto.

'Ihe end of the inner shell or conduit remote from the gas receiving endis closed and supported from the intermediate shell 65 by means of abaille member 1U, the outer flange or portion oi! which may be welded tothe intermediate shell 6I and the middle portion 1l of which telescopeswithin the end of the inner conduit. The inner conduit may also beprovided with a restriction or contracting member which may be in theform of a sleeve 12 having an outer substantially cylindrical portion 13welded to the inner face of the conduit 84 and having an annular portion14 of reduced diameter. A restriction or obstruction to gas flow of anyother suitable construction may be employed in the conduit G4, or therestriction may be omitted, if desired.

ing a resonator and pressure equalizing chamber 8| which communicateswith the space between the conduit 64 and intermediate shell by means ofa series o! holesl or apertures 82 in the intermediate shell 65. At theother side of the baille 80 is formed a chamber or passage 88 whichreceives gases from the space between the conduit and intermediate shellthrough a series of apertures 84 in the intermediate shell located infront of the baille 10 and the gases and sound waves pass out of thechamber 83 through another series of holes or apertures 85 located inrear of the baille 10. The gases thus pass into a chamber 86 arrangedwithin the intermediate shell between the baille 10 and atransversebaille 81 having a restricted opening 88 which may form` a support forthe inner end of the tail pipe, or

which may form with the end head 62 a small expansion chamber 89 in casethetail pipe does not extend inwardly beyond the inner end of. thetubular extension or duct 90 of the head 6M Holes or apertures 15, 16and 82 in the inner conduit and intermediate shell may, ii' desired, beprovided with louvers or deilecting members 92, as clearly shown in Fig.6, so that the gases and sound waves discharged through these apertureswill be discharged in directions substantially tangential to the conduitand shell in which the apertures are formed.

In Fig. 7, we have illustrated a slight -modiilcation of theconstruction shown ln Fig. 5, by replacing the baille 88 shown in Fig. 5by a bafiie 94 which has a series of apertures 95 therein. Consequently,a chamber 9.6 is formed between the baille 94 and the end head 62, whichserves as an expansion chamber, if the tail pipe 91 of the muiilerextends from the duct 90 into the central opening 98 of the baille 94.

In the operation of the muffler shownn Figs. 5 to 7, some of the gasesand sound waves passing into the inner conduit 64, will dischargethroughv openings 15 therein while other gases 'pass through therestriction 14 and then through openings 16 and these gas pulsations andsound waves will, consequently, be somewhat out of phase with those thathave passed through the openings 15. A further silencing of sound wavesand equallzing-of gas flow results from the passage of sound Waves andgases into the resonator chamber 8|. Peaks of gas pressure waves orimpulses which enter into the chamber 8| are then discharged from thischamber during the troughs or low pressure periods, resulting in a moreuniform flow of gases through the aper- Ctures 64, the chamber 83andinto the chamber 86. From the chamber 86 further expansion of gasesand silencing of sound waves is effected by means of the chambers 89 or96, and consequently, there will be a comparatively uniform ow ofexhaust gases through the tail pipe 91. 'I'he sound waves which havepassed hito the muiiler will have been so interfered with and reduced bythe'resonator chamber 8| and other parts of the muiiler that the gasdischarged from the end of the tail pipe will be comparatively free fromaudible sound waves.

In Figs. 8 to 10 inclusive, we have shown another modifled form ofmuiller, which is very similar to that shown in Figs. 5 to 7. Thismuiiler includes an outer shell and end heads 0| |02, which are providedwith annular shoulders to support the ends of an intermediate shell |03.The inner shell or conduit |04- ls supported vwithin the intermediateshell |03 by means of baiiies I 05,and |06, the baille |06 closing theend of the inner conduit or shell |04 and the baille being provided withan aperture |01 which is preferably of smaller diameter than theinternal diameter of the conduit |04. 'Ihe inner shell or conduit |04 isalso provided with a restriction or contraction' |08 similar to thatdescribed in connection with Figs. 5 and 6 and acting in a similarmanner in connection with apertures |09 and ||0 located before and.behind the restriction |08. An annular baille is provided between theintermediate and outer shells forming a resonator and expansion chamber||2 into which gases and sound waves may enter through a series ofapertures ||4 which are formed in the intermediate shell aheadv of thebaille |05. The intermediate shell is also provided with apertures 5communicating with a chamber IIB formed in rear of the annular bailleand the gases and sound waves pass out of the chamber I|6 through aseries of openings or Aapertures ||1 into a chamber ||8 from which theyare discharged from the muiiler. The apertures |09, ||0 and ||4 may beprovided with louvers or deilecting parts 9, as shown in Figs. 9 and 10.

In the operation of this mulller, gases and sound waves entering themuiiler through the inlet head |0| enter into the expansion chamber |20and the peaks or crests of pressure impulses vor waves, together withsound waves immediately enter through the apertures ||4 into theresonator and pressure equalizing chamber l2. The reduced pressure wavesor impulses together with sound waves which have been materially reducedby destructive interference from sound waves discharged from theresonator chamber |2 then pass into the conduit |04, the reduced opening|01 of the baille |05 serving to hold back to a limited extent the gasesand sound waves in the chamber |20 to obtain the full benefit of theresonator and equalizing chamber I2.. A part of the gas pressureimpulses and sound Waves pass out of thev openings |09 and other gasimpulses and sound waves will pass out of apertures ||0 after travellingthrough the restriction |08, and will be somewhat out of phase withthose discharged from the apertures |09. This results in an equalizingof the flow of gases as they pass through the apertures ||5 and also ina material reduction oi' noises, ilrst by the resonator chamber |I2 andthen by the action of the other parts of the mullier which have beendescribed. FurvH6 and H8.

In Fig. 11, there is shown a baille |25 arranged between theintermediate shell |03 and the inner shell or conduit |04, which differsfrom the baille |05 only in that there are provided in the transversewall of the outer portion of the baille a series of apertures |26,through which some gas and sound waves may pass directly from thechamber |20 into the chamber or passage formed between the inner conduit|04 and the intermediate shell |03. For certain types of engines, theseapertures assist materially in taking out sound waves of certainfrequencies in that there will be discharged into the space between theinner conduit and intermediate shell some gas impulses and soundwaves,which will be out of phase with impulses and sound waves enteringthrough the in the case o! gas pressure impulses, to build up a pressurein the portion ci the conduit ahead. of the restrictions before apressure is built up in the part oi' the conduit in rear oi therestriction, so that an outward iiow through perforations or openingsahead of the restriction takes place before a flow through periorationsor openings in rear of the restriction can Itake place. In this manner.the dow of gases through the mutller is also equalized, and since soundwaves follow the flow oi' gases, interference of sound waves alsoresults for this reason.

We claim as our invention:

1. A muiiler including an outer shell, heads closingthe ends of saidshell, one oi said heads having an opening for receiving gases and soundwaves, and the other head having a discharge opening, an intermediateshell connecting said heads and spaced from said outer shell, and aninner shell concentrically arranged within said intermediate shell andhaving one end arranged to receive gases and having the other end closedand being provided with apertures through which V gases may flow intothe space between said inner and intermediate shells, a transversepartition arranged intermediate the ends of said intermediate shell andseparating one part thereof from another and also extending across saidinner shell in rear of said apertures therein and forming the closurefor said closed end of said inner shell, said intermediate shell havingtwo sets of apertures, one located in advance of said partition and theother located in rear of said partition, means forming a concentricpassage about said intermediate shell and connecting said apertures ofsaid intermediate snell for conducting gases exteriorly of saidintermediate shell from one set of apertures to the other, saidvoutershell and said intermediate shell forming between them a resonatorchamber communicating with the interior of said intermediate shell forreceiving pressure pulsations therefrom without forming a Dart of theiiow passage of gases through said muffler.

2. A muiiler including a perforate inner shell forming a passage forreceiving gases at one end thereof and having the other end thereofclosed, a pair of intermediate shells arranged about said inner shelland spaced therefrom and from each other to form passages for gasesbetween said shells, the inner of said intermediate shells re-` ceivinggases from perforations in said inner shell and forming with said innershell a longitudinal passage for gases and having an apertured zonespaced in a longitudinal direction from the perforations of said innershell and through which gases now from said passage between said innershell and the inner oi said intermediate shells into the space betweensaid intermediate shells and having other apertures through which gasesare discharged from said space, and an outer shell arranged about saidintermediate shells and forming therewith a resonator chambercommunicating with the passage between said intermediate shells andarranged exterior to the path of gases dowing through the muiiler.

3. A muiller including an outer shell, heads closing the ends ofosaidshell, one of said heads having an opening for receiving gases and soundwaves, and the other head having a. discharge opening, an intermediateshell connecting said heads and spaced from said outer shell, and aninner shell arranged within said intermediate shell and having one endarranged to receive gases and having the other end closed and beingprovided with apertures through which gases may flow into the spacebetween said inner and intermediate shells, a transverse baille dividingthe space between said outer and intermediate shells into a resonatorchamber and iiow pamage, said intermediate shell having aperturesthrough which gases may enter and leave said resonator chamber and otherapertures through which gases may pass from the space between said innerand intermediate shells into said ow passage, and a transverse bailleextending across said intermediate shell and arranged rearwardly of saidapertures in said intermediate shell, said intermediate shell alsohaving apertures rearwardly of said baille through which gases flow fromsaid iiow passage to the interior of said intermediate shell fordischarge from said muiller.

4. A mufiler including an outer shell, heads closing the ends of saidshell, one of said heads having an opening for receiving gases and soundwaves, and the other head having a discharge opening, an intermediateshell connecting said heads and spaced from said outer shell and formingtherewith a resonator chamber, said intermediate shell having aperturesadjacent to said gas receiving head and communicating withsaid resonatorchamber, an inner shell arranged within said intermediate shell with itsleading end open and disposed in rear of said apertures and arranged toreceive gases from said intermediate shell and having the otherend'closed and havlng two sets of apertures through which gases may flowout of said inner shell after their pas- Sage into said inner shell fromsaid intermediate shell, a restriction in said inner shell arranged withone set oi' said apertures arranged ahead oi said restriction and withother set of apertures arranged in rear oi said restriction, and meansin said muiiier for conducting out oi' the muliler gases discharged fromsaid inner shell.

5. A muiiler including an outer shell, a head closing an end of saidshell and having an opening into which a gas conducting pipe may extend,a second shell arranged Within said outer shell, and a support for saidsecuring second shell to the muliler adjacent to said head and having anaperture therein spaced from said head and into which the inner end ofsaid gas conducting pipe fits snugly to provide two spaced supports forsaid pipe.

6. A muiller including an outer shell, a head closing an end of saidshell and having an opening into which a gas conducting pipe may extend,a second shell arranged Within said outer shell, and a supporting memberfor said second shell, which is supported on said mumer from said headand which extends into the interior of said mui'iler into spacedrelation to said head, said supporting member including an annularshoulder engaging said shell and an opening of substantially the samediameter as the opening in said head and in alinement therewith and intowhich the inner end of said pipe may extend to produce a rigidconnection between said pipe and said muiiler.

7. A mufilerincludng a series of shells arranged one within another andforming between them spaces for the passage of gases and sound waves,the inner of said shells being arranged to receive gases at one endthereof and having the other end thereof closed and having a restrictedperforate zone to permit gases to discharge into the space between saidinner shell and the next shell, said next shell having a set ofapertures spaced lengthwise from the perforations of said inner shelland disposed in advance o! the closed end of said inner shell, throughwhich gases pass after passing lengthwise of the space between saidinner and said next shell, said next shell also n having another set ofapertures in rear of the closed end of said inner shell through whichgases pass into the interior of said next shell for discharge from saidmuiiler, a transverse partltion arranged in said next shell between saidsets of apertures, and a side branch resonator chamber formed by some ofsaid shells and connected with a'gas passage of said muiller.

8. A muiller includingan outer shell, headsL heads and spaced from saidouter shell and forming therewith a resonator chamber, said intermediateshell having apertures adjacent to said gas receiving head andcommunicating with said resonator chamber, an inner gas receiving shellarranged within said intermediate shell with its inlet end disposed inrear of said apertures and arranged to receive gases from saidintermediate shell and having the other end closed and having aperturesthrough which gases may flow out of said inner shell, and means in saidmullier for conducting out of the muiiler gases discharged from saidinner shell.

GAIL C. STARKWEATHER. LUCIEN L. HAAS.

